Sequential injection methods referred to below as SEFI-methods (Sequential Fuel Injection) are carried out in internal combustion engines wherein each cylinder is provided with an injection valve. The crankshaft position must be monitored in order that each injection valve is driven at the desired time point within a work cycle. The crankshaft position is monitored by scanning marks on a transducer wheel which rotates synchronously with the crankshaft. A work cycle extends over 720.degree. or over two crankshaft rotations. As a consequence thereof, the crankshaft angle measured with the aid of the transducer wheel cannot clearly be assigned to the first or second part of the work cycle without an additional signal. The additional signal is supplied by a camshaft sensor which scans a mark on the crankshaft which rotates only once for two crankshaft rotations. Before an unequivocal synchronization is established, it is not possible to drive injection valves to the actual desired time point.
Metering fuel in accordance with an SEFI-method can therefore only be started in a delayed manner after the engine is started and this is most undesirable. For this reason, conventional methods provide that all injection valves are driven to each provide a preinjection at the start of the injection method. More specifically, the preinjections are only then supplied when adequate fuel pressure has built up. If the crankshaft position can be precisely determined shortly after the preinjection is supplied by the occurrence of the signal from the camshaft sensor and if then the regular fuel metering is permitted, then ignition will be missed in different cylinders because of an overenriching of the mixture. In order to overcome this disadvantage, the decision has been made that the regular fuel metering is delayed after supplying the preinjection for such a time that a double injection into a cylinder is avoided with certainty. Accordingly, European Patent 0,058,561 discloses a fuel injection control method wherein the preinjection is delayed after the start at least for a crankshaft angle of 720.degree. before beginning with fuel metering pursuant to the SEFI-method. A disadvantage with this kind of method is that various cylinders receive no fuel in the time interval between the end of the preinjection and the beginning of the regular fuel metering.